22 R. W. CROSSKEY 



propleuron is almost always bare, and in the Goniinae hairing of the propleuron 

 is almost entirely confined to certain Blondeliini and Neaerini (the propleuron 

 appears to be consistently bare in the tribes of Goniinae in which the pre-alar 

 seta is very large) . 



prosternal membrane. The extensive membranous area on either side of the 

 prosternum (Text-fig. 9). 



This membrane is only of taxonomic value according to whether it is bare 

 (as in the overwhelming majority of Tachinidae) or haired. Hairs on the 

 prosternal membrane occur mainly in Rutilia subg. Chrysorutilia and a few 

 allied Rutiliini, but elsewhere are of very rare occurrence (found, for example, 

 in some Chaetophthalmus species). 



prosternum. The strong ventral plate of the thorax lying between and in front 

 of the fore coxae (Text-fig. 9). 



One of the most important taxonomic characters in the Tachinidae is 

 provided by the presence or absence of vestiture on the prosternum. The 

 vestiture when present consists of fine hairs or a few strong setulae on each 

 side of the middle part of the prosternum which are directed outwards or 

 downwards, or of some soft hair on the anterior corners (as in some Rutilia 

 and some Chaetophthalmus species). The prosternum is totally bare in 

 (apparently) all Phasiinae, almost all Proseninae and the great majority of 

 Tachininae, but is almost universally haired or setulose in the Goniinae (even 

 if the vestiture consists only of a single hair on each side) ; a few Goniinae have 

 the prosternum bare, these including several genera of Blondeliini and 

 Bkpharella in the Sturmiini. 



prostigmatic seta(e). One or more strong setae anterolaterally on the thorax 

 below the anterior spiracle (mesopleurospiractdar setae of Townsend, Substig- 

 matikalborsten of Mesnil) (Text-figs 7 & 8). 



One or more of these setae almost always present and directed upwards. 

 The genus Peribaea (tribe Siphonini) is very exceptional in having two equally 

 strong prostigmatic setae of which the upper one is directed upwards and the 

 lower one strongly downwards (an arrangement apparently found nowhere else 

 in the family) (Text-fig. 8). 



pteropleural seta. A seta standing on the upper edge of the pteropleuron 

 (Text-fig. 7). 



Presence or absence of this seta can provide an important character at various 

 levels. Sometimes it is only weakly differentiated from the general pteropleural 

 hairing and sometimes is duplicated. The seta is absent or very weak in nearly 

 all Phasiinae and Proseninae and strong in nearly all Goniinae; in the Tachininae 

 it is developed to various degrees in different genera or tribes, and if strong its 

 actual size in relation to other structures is sometimes taxonomically useful 

 (e.g. in African Linnaemya). 



pteropleuron. The area of the side of the thorax immediately behind the 

 mesopleuron and below the wing base (Text-fig. 7) . 



The only use of this area in taxonomy (apart from the pteropleural seta, q.v.) 

 is for the extent of its hair vestiture. Normally the anterior half of the 



